Washing your car with a garden hose feels harmless, but San Diego's water supply carries more dissolved minerals than most people assume, and that has real consequences for your paint.
Why San Diego's Water Is So Hard
Much of the region's water is imported from the Colorado River, which carries a higher mineral content than local groundwater in a lot of other parts of the country. That translates directly to harder tap water coming out of your hose.
What Hard Water Actually Does to Paint
When mineral-heavy water is left to air dry on the surface, the water evaporates and leaves the dissolved calcium and magnesium behind as spots. Left long enough in the sun, those mineral deposits can etch into the clear coat rather than just sitting on top of it.
Why DIY Washing Keeps Making It Worse
Washing with a hose and letting the car air dry, even with good intentions, reintroduces the same hard-water spotting every time. The mineral content doesn't change wash to wash, so the damage compounds gradually rather than happening all at once.
What Professional Detailers Use Instead
An RO/DI water system filters out the dissolved minerals before the final rinse, so the water evaporates clean without leaving spots behind. It's a standard part of a proper detail and one of the simplest ways to stop the problem at the source.
If you're already seeing faint water spotting on your paint, it's worth having it assessed before it etches any deeper.